Ultrasound imaging apparatus are generally used by doctor to inspect tissues inside human body. The doctor can place an ultrasound probe onto the surface of the skin corresponding to a tissue to obtain ultrasound images of the tissue. Due to its characteristics of safety, convenience, non-invasion and low cost, etc, the ultrasound imaging has become a main assisting means for diagnosis.
Obstetrics is one of the fields where the ultrasound imaging is widely applied. With the use of the ultrasound imaging device, the affects to mother and fetus by the X rays can be avoided. Therefore, the ultrasound imaging device has better application value than other imaging device. By the ultrasound imaging device, not only the morphology of the fetus can be observed and measured, but also various information regarding the physiology or pathology of the fetus, such as the respiration or urination of the fetus, can be obtained to evaluate the health and growth states of the fetus.
When inspecting the nervous system of the fetus, the corpus callosum and the cauda cerebella are very important objects. The corpus callosum is the biggest connection fiber between the cerebral hemispheres and is responsible for the communication between the cerebral hemispheres. Deficiency or hypogenesis of the corpus callosum will lead to several complications, such as epilepsy, feeblemindedness or dyskinesia, etc. Deficiency or hypogenesis of the cauda cerebella is the symptom of Dandy-Walker syndrome. 50% of patients with the Dandy-Walker syndrome have mental retardation and feeblemindedness, and are usually accompanied by chromosome abnormalities and other deformities, with poor prognosis and high mortality rate.
Accordingly, the abnormalities of the corpus callosum and the cauda cerebella are represents of critical diseases. If they were not found during the prenatal examination, they would bring huge mental and economic burden to the family of the patient and the society. Besides, for the hospital where the examination is carried out, they may lead to medical tangles. However, the corpus callosum and the cauda cerebella are very easy to be misdiagnosed or missed during the inspection of the nervous system of the fetus. The reason is that it is very difficult to obtain the median sagittal section image of the fetus, which is the best image for observing the corpus callosum and the cauda cerebella, by a conventional two-dimensional ultrasound imaging due to the affects of the factors such as fetal position, amniotic fluid, obstruction of the nasal bone and skill of the doctors, etc. Even if the image of the median sagittal section was obtained, it would take a long time. Accordingly, many doctors have to indirectly inspect the corpus callosum and the cauda cerebella by images of other sections (such as, the cerebellum section or the thalamus section, etc.), therefore the misdiagnosis and the missed diagnosis are easy to occur.
Recently, with the widespread use of the three-dimensional ultrasound imaging, some doctors perform a three-dimensional scanning on the fetus starting from the biparietal diameter section, find out the image of the median sagittal section of the fetus by geometric transforms of obtained 3D ultrasound image data, such as manual rotation and translation, etc, and then inspect the corpus callosum and the cauda cerebella through this median sagittal section image. Although the median sagittal section image obtained by this way may have relatively lower quality than a conventional two-dimensional image, the corpus callosum and the cauda cerebella can be relatively clearly displayed, and the abnormalities of the corpus callosum and the cauda cerebella can be determined quickly and exactly. However, in order to be able to find out the median sagittal section in three-dimensional space by manual rotation and translation, the doctors must understand the three dimensional space very well. But, most doctors have no science and engineering background and lack of understanding to a three dimensional space. Therefore it is very difficult for them to manually find out the median sagittal section image from a volume data. Although it has been developed for many years, only few doctors have this skills.